From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D4B9C433DF for ; Mon, 8 Jun 2020 22:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 150B72074B for ; Mon, 8 Jun 2020 22:44:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=codeweavers.com header.i=@codeweavers.com header.b="cL+QJMZ5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726803AbgFHWoh (ORCPT ); Mon, 8 Jun 2020 18:44:37 -0400 Received: from mail.codeweavers.com ([50.203.203.244]:57792 "EHLO mail.codeweavers.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726734AbgFHWog (ORCPT ); Mon, 8 Jun 2020 18:44:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=codeweavers.com; s=6377696661; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=SK/bJp3BIMRifQIcn0vlilfkReFXQUZN2KbNTvSxsvo=; b=cL+QJMZ5fuutY9vVv734NHtG71 FV593HQhXx79pvYX/btGAHyuXJ0fZk9c1N2whgefGL+MBtsuTuo6I20wjtUbCp+/xL8aOPn3aiLGe ypo8M/ScpUpmA8W9+q12xfFGIHpRLey0m9HkADTJwJDXmETgXO3CZ0ZrV0fxHF6TXfhA=; Received: from cpe-107-184-2-226.socal.res.rr.com ([107.184.2.226] helo=zen.bslabs.net) by mail.codeweavers.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jiQVM-0004n1-RC; Mon, 08 Jun 2020 17:44:34 -0500 From: Brendan Shanks To: linux-kernel@vger.kernel.org Cc: ricardo.neri-calderon@linux.intel.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, ebiederm@xmission.com, andi@notmuch.email, Babu.Moger@amd.com, Brendan Shanks Subject: [PATCH v3] x86/umip: Add emulation/spoofing for SLDT and STR instructions Date: Mon, 8 Jun 2020 15:44:24 -0700 Message-Id: <20200608224424.7259-1-bshanks@codeweavers.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add emulation/spoofing of SLDT and STR for both 32- and 64-bit processes. Wine users have found a small number of Windows apps using SLDT that were crashing when run on UMIP-enabled systems. Reported-by: Andreas Rammhold Originally-by: Ricardo Neri Signed-off-by: Brendan Shanks --- v3: Use (GDT_ENTRY_TSS * 8) for task register selector instead of harcoding 0x40. arch/x86/kernel/umip.c | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c index 8d5cbe1bbb3b..166c579b0273 100644 --- a/arch/x86/kernel/umip.c +++ b/arch/x86/kernel/umip.c @@ -244,16 +244,35 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst, *data_size += UMIP_GDT_IDT_LIMIT_SIZE; memcpy(data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE); - } else if (umip_inst == UMIP_INST_SMSW) { - unsigned long dummy_value = CR0_STATE; + } else if (umip_inst == UMIP_INST_SMSW || umip_inst == UMIP_INST_SLDT || + umip_inst == UMIP_INST_STR) { + unsigned long dummy_value; + + if (umip_inst == UMIP_INST_SMSW) + dummy_value = CR0_STATE; + else if (umip_inst == UMIP_INST_STR) + dummy_value = GDT_ENTRY_TSS * 8; + else if (umip_inst == UMIP_INST_SLDT) + { +#ifdef CONFIG_MODIFY_LDT_SYSCALL + down_read(¤t->mm->context.ldt_usr_sem); + if (current->mm->context.ldt) + dummy_value = GDT_ENTRY_LDT * 8; + else + dummy_value = 0; + up_read(¤t->mm->context.ldt_usr_sem); +#else + dummy_value = 0; +#endif + } /* - * Even though the CR0 register has 4 bytes, the number + * For these 3 instructions, the number * of bytes to be copied in the result buffer is determined * by whether the operand is a register or a memory location. * If operand is a register, return as many bytes as the operand * size. If operand is memory, return only the two least - * siginificant bytes of CR0. + * siginificant bytes. */ if (X86_MODRM_MOD(insn->modrm.value) == 3) *data_size = insn->opnd_bytes; @@ -261,7 +280,6 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst, *data_size = 2; memcpy(data, &dummy_value, *data_size); - /* STR and SLDT are not emulated */ } else { return -EINVAL; } @@ -383,10 +401,6 @@ bool fixup_umip_exception(struct pt_regs *regs) umip_pr_warn(regs, "%s instruction cannot be used by applications.\n", umip_insns[umip_inst]); - /* Do not emulate (spoof) SLDT or STR. */ - if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT) - return false; - umip_pr_warn(regs, "For now, expensive software emulation returns the result.\n"); if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size, -- 2.26.2